Passive frequency measuring circuit comprising a number of frequency discriminators to obtain a digital code representing the frequency of an applied r.f. signal. Each discriminator is tuned to different frequency ranges, and provided with a plurality of similar frequency analysers for

A mixer is provided with a first waveguide part for the transmission of an input signal to be converted to a lower frequency band and with a second waveguide part for the transmission of a signal supplied by a local oscillator. The first and second waveguide parts open into a cavity

With a method for the fabrication of multilayers a laminate is obtained by the stacking of layers, which are formed by a carrier provided with a conductor pattern and interleaved by adhesive layers. The laminate is subjected to a process which is carried out in at least three phases: in